linux-kernel - Re: [PATCH 1/2] mtd: atmel_nand: use __iowrite32

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Date:	Tue, 21 Oct 2014 12:20:06 +0200
From:	Herve Codina <herve.codina@...ad.com>
To:	Josh Wu <josh.wu@...el.com>, Vinod Koul <vinod.koul@...el.com>,
	"linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:	David Woodhouse <dwmw2@...radead.org>,
	Brian Norris <computersforpeace@...il.com>,
	Jingoo Han <jg1.han@...sung.com>,
	EzequielGarcia <ezequiel.garcia@...e-electrons.com>,
	Mark Brown <broonie@...aro.org>,
	Nicolas Ferre <nicolas.ferre@...el.com>,
	BartlomiejZolnierkiewicz <b.zolnierkie@...sung.com>,
	Bo Shen <voice.shen@...el.com>,
	Fabio Estevam <fabio.estevam@...escale.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Michael Grzeschik <m.grzeschik@...gutronix.de>,
	Josh Triplett <josh@...htriplett.org>,
	Wei Yongjun <yongjun_wei@...ndmicro.com.cn>,
	HuangShijie <shijie8@...il.com>,
	Michael Opdenacker <michael.opdenacker@...e-electrons.com>
Subject: Re: [PATCH 1/2] mtd: atmel_nand: use __iowrite32_copy for 32 bitcopy

Hi,

I didn't go deeper in atmel_nand.c code to see other accesses but old
copy use writel_relaxed which is a macro to __raw_writel((__force u32)
cpu_to_le32(v),c)

__iowrite32_copy use directly __raw_writel(*src++, dst++)

So we skip cpu_to_le32. Is it ok for all system using atmel_nand ?

Best regards,
Herve Codina


Le 21/10/2014 12:03, Josh Wu a écrit :
> Hi, Vinod
> 
> On 10/21/2014 12:06 AM, Vinod Koul wrote:
>> The driver was also using own method to do 32bit copy, turns out
>> we have a kernel API so use that instead
>>
>> Signed-off-by: Vinod Koul <vinod.koul@...el.com>
> 
> Thanks for the patch.
> Acked-by: Josh Wu <josh.wu@...el.com>
> 
> BTW, is there any similar kernel API that is for the read from io?
> 
> Best Regards,
> Josh Wu
> 
>> ---
>>   drivers/mtd/nand/atmel_nand.c |   10 +++-------
>>   1 files changed, 3 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c
>> index e321c56..b03e80d 100644
>> --- a/drivers/mtd/nand/atmel_nand.c
>> +++ b/drivers/mtd/nand/atmel_nand.c
>> @@ -265,14 +265,10 @@ static void memcpy32_fromio(void *trg, const void __iomem  *src, size_t size)
>>   		*t++ = readl_relaxed(s++);
>>   }
>>   
>> -static void memcpy32_toio(void __iomem *trg, const void *src, int size)
>> +static inline void memcpy32_toio(void __iomem *trg, const void *src, int size)
>>   {
>> -	int i;
>> -	u32 __iomem *t = trg;
>> -	const u32 *s = src;
>> -
>> -	for (i = 0; i < (size >> 2); i++)
>> -		writel_relaxed(*s++, t++);
>> +	/* __iowrite32_copy use 32bit size values so divide by 4 */
>> +	__iowrite32_copy(trg, src, size/4);
>>   }
>>   
>>   /*
> 
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